Further results when interactions between the presence of observer and month are taken into account for steel vessels

Interactions between the presence of an observer and month are investigated for both anchovy and sardine fisheries. The aim is to ascertain whether the effect of the presence of an observer still remains significant after these interactions have been taken into account, and also how this effect varies over a twelve month period. The evaluation of these interactions and approach gives a clear indication of a trend in the effect of the observer on catch rates for each month. Using the trend that emerged from the interactions, the observer factor was redefined with three levels, two levels indicating the presence of an observer for each six month period of the year and the other level indicating absence of an observer

2021 updated analysis of the sea ice concentration (SIC) in research blocks 4 (RB4), and 5 (RB5) of Subarea 48.6 with sea surface temperature (SST) and winds

Ice condition in the subarea 48.6, Southern OceanIn RB5, the SICs in Feb. 2021 were the highest and the SSTs were the lowest for the years 2016-2021. In March 2021, the highest SICs decreased to nearly the longterm average while the SST increased accordingly. In the same year, the SICs and SSTs had two peaks in Feb. and March respectively. In RB4, the SICs during Jan.- Feb (Austral summer) in 2021 were also the highest since 2016. The sharp spikes of SST (rapid increasing SST) had become smaller year by year from 2017 to 2021, which indicates that the SSTs had a cooling phase in 5-6 year periodical cycles corresponding to an increasing trend in SICs. Spatial dynamics of SICs with SSTs contour of -1.8°C and -0.8°C were analyzed. It was found that the ice edges are at approximately -1.8°C and partially broken ices exist between -1.8°C and -0.8°C when comparing imagery by GIBS and SICs distribution by AMSRs with SSTs by NOAA. Daily wind stick plots indicate that the eastward winds could encourage the off-shore Ekman transport at the end of Feb. and the beginning of Mar. which resulted in late (slow) ice retrieval in 2021

An indirect investigation of the possible influence of port on the estimation of observer effects on catch rates in the pelagic fishery

Earlier GLM analyses of catch per hour data for sardine and anchovy to determine observer effects have suggested statistically significant increases in this catch rate with observers on the vessels over January-to June for the sardine fishery, and over May to October for the anchovy fishery (Somhlaba et al. 2006). This in turn has raised the possibility that this may reflect (and provide quantification of the extent of) slippage in the catching operations conducted without observers present

Overall results for the effect of the presence of an observer on catches made by the pelagic fleet

The analysis of the observer data for the pelagic fishery is taken further for the complete data base from 1999 to 2004. Previously the analysis had been based on steel vessels (Somhlaba et al., 2005); those findings showed that there were statistically significant positive effects on catches given the presence of an observer on the steel vessels. The results below include the analysis of the combined data for all three categories of vessels: bait, ordinary and steel vessels. Sardine and anchovy data were analysed in detail using one model but with two different error structures: one lognormal (henceforth termed LogCPUE) and the other Poisson (henceforth termed catch)

Preliminary results of observer effect on pelagic fleet taking into account observer data from 1999 to 2011

A detailed update of the study of the data collected by scientific observers onboard the pelagic vessels is currently underway. The use of small pelagic commercial data base and an observer data base to investigate the effect of observers onboard commercial vessels has been an ongoing study since the mid-2000s (e.g. see Somhlaba et al, 2005, 2006, 2007). This paper updates those studies by including data from the more recent years 2008 to 2011